1. Field of the Invention
The present invention relates to high voltage fuses, and more particularly, to means to assure that a fuse cannot be re-latched into a fuse mounting after fuse operation.
2. Description of the Prior Art
High voltage expulsion fuses of the dropout type are well known in the art as exemplified by U.S. Pat. No. 3,267,235--Barta. Such high voltage fuses are typically mounted between two mounting terminals that are adapted to allow the fuse to be released from one mounting when the fuse operates so that the fuse will pivot away from one terminal and provide a visual indication of fuse operation.
This dropout function is achieved by a spring biased arcing rod which is released when a fusible element at one end melts so that the arcing rod moves very rapidly under the urging of the spring until the other end of the arcing rod pierces a seal at the end of the fuse and engages a fuse release assembly mounted on the end of the fuse causing the fuse to be released from the mounting. However, since the fuse typically pivots free of the top terminal because of the force of gravity, it is necessary for the arcing rod to engage the fuse release assembly for a predetermined period of time to allow the fuse sufficient time to move under the forces of gravity so that the fuse release assembly does not re-engage the mounting terminal before the fuse drops out. In addition, it is desirable for the end of the arcing rod to remain extending out of the fuse so that the operated fuse cannot inadvertently be re-latched into the closed position, and to indicate that the fuse has operated.
Accordingly, it has been discovered that it would be a desirable advance in the art to provide a means for engaging the rod when it moves to the end of the fuse tube to prevent the arcing rod from bouncing or falling away from the end of the tube.